1. Field of the Invention
The present invention relates to an AC generator for a vehicle and, particularly, a rectifier unit arrangement of an AC generator.
2. Description of the Related Art
In an ordinary vehicle AC generator, a rectifier unit is mounted therein to rectify AC voltage induced in a stator winding when a rotor rotates. For example, if the stator winding is a three-phase winding, a pair of diodes is necessary for every phase. That is, six diodes, or eight diodes if neutral-point power is taken out, are necessary in total for a three-phase full-wave rectifier unit. U.S. Pat. No. 5,883,450 and JP-A-9-135558, which corresponds to U.S. patent application Ser. No. 08/745,775, disclose a rectifier unit which includes a positive cooling fin having positive diodes fixed thereto, a negative cooling fin having negative diodes fixed thereto, and a terminal member. The terminal member connects one end of the positive diodes and one end of the negative diodes together and also connects leads of the stator winding to portions around the outer periphery of the positive cooling fin or portions formed at the outer periphery of the negative cooling fin.
In the above rectifier unit, the terminal member is disposed at portions around the outer periphery of the positive cooling fin or portions formed at the outer periphery of the negative cooling fin. If water or a foreign particle such as an electrolyte gets into the inside of the AC generator, it may flow along the positive cooling fin into spaces formed between the terminal member and the outer periphery of the positive cooling fin, causing insulation failure.